Insulated cartridge case and ammunition, method for manufacturing such cases and ammunition, and use of such cases and ammunition in various different weapon systems

ABSTRACT

The invention relates to a cartridge case ( 2 ) and ammunition round ( 1 ) primarily for electrothermal and/or electrothermochemical weapon systems, which round comprises the said cartridge case. According to the invention, the casing ( 10 ) of the cartridge case comprises or consists of one or more insulated or insulating shells, layers or surfaces ( 11, 12, 13 ) for, at least electrically, insulating the casing of the cartridge case from the barrel ( 14 ) of the weapon system and also preferably from at least the bottom ( 16 ) and/or firing device ( 5 ) of the ammunition round as well, but preferably also from the rest of the ammunition round, when the round is used, and also preferably from at least the bottom and/or firing device of the ammunition round as well, but preferably also from the rest of the ammunition round, when the round is stored and handled. The invention also relates to a method for manufacturing an, at least electrically, insulated or insulating cartridge case and an ammunition round primarily for electrothermal and/or electrothermochemical weapon systems, which round comprises such a cartridge case, and also use of such insulated or insulating cartridge cases and ammunition rounds in different weapon systems, but preferably in electrothermal and electrothermochemical weapon systems.

TECHNICAL FIELD

The present invention relates to a cartridge case and ammunition roundprimarily for electrothermal and/or electrothermochemical weaponsystems, which round comprises the said cartridge case.

The invention also relates to a method for manufacturing such acartridge case and an ammunition round primarily for electrothermaland/or electrothermochemical weapon systems, which round comprises thesaid cartridge case.

The invention also relates to use of the cartridge case and theammunition round in other more conventional weapon systems than the saidelectrothermal and/or electrothermochemical weapon systems, butpreferably in electrothermal and electrothermochemical weapon systems.

PROBLEMS AND BACKGROUND OF THE INVENTION

Various different propulsion principles exist today for acceleratingprojectiles through the barrel of a weapon system. The main divisionbetween these principles is based on whether projectile propulsion takesplace by means of gas operation, electric operation or via a combinationof these, at the same time as the propulsion principle(s) used in turnessentially determine which problems may arise in the different weaponsystems.

Gas-operated weapon systems normally mean those systems which utilizethe combustion gases which are formed after ignition of the propellantconcerned for the shell, which propellant may now be liquid, solid orgaseous, although powder is still usually used. For example, in aconventional weapon, an ammunition round is fired by means of a firingdevice, normally a fuse, which ignites a propellent charge which, oncombustion, develops a propellent gas quantity which is sufficientlypowerful and expansive to accelerate the projectile rapidly out throughthe barrel of the weapon.

Electrically driven weapon systems instead utilize short electric pulseswith high voltage and/or high current intensity in order to fire andpropel the shell in ammunition adapted especially for electricoperation.

In recent years, weapon systems based on combinations of both gasoperation and electric operation, such as, for example, cannons whichcomprise either electrothermal propulsion or electrothermochemicalpropulsion, what are known as ETC cannons, have become increasinglyimportant. In ETC cannons, use is made of, for example, electricalenergy from a high-voltage source in order to bring about the actualignition of the propellent charge, and then of on the one hand chemicalenergy from the combustion of this propellent charge and on the otherhand electrical energy in the form of one or more pulses in order tosupply more energy to the propellent gas in the form of plasma formationfrom the latter or via the creation of an electric potential differencealong the barrel in order to increase the speed of the projectile.

In many hitherto known electrothermochemical weapon systems, theconventional fuse is replaced by a plasma generator. The plasmagenerator is filled with a preferably metal material which, via theelectric pulses, is heated, vaporized and finally partly ionized, aplasma being produced, which, depending on the type of plasma generator,flows out through the front opening of the plasma generator or through anumber of openings along its sides, what is known as a “piccolo”. Thevery high temperature (roughly 10,000° K) of the plasma influences thecombustion of the propellant in several positive ways, which togetherresult in a desired higher muzzle velocity of the projectile.

Rather briefly, it can be said that a typical modern ETC cannon consistsof a cannon, the shell projectiles of which are essentiallypowder-gas-propelled, but where the shell is fired by means of electricignition and its projectile is given an extra “push” via the plasmaformation in connection with combustion of the propellent charge.However, there are also ETC cannons in which, after firing by means of aconventional fuse add “normal” combustion of the powder charge carriedout subsequently, extra electrical energy is supplied to the projectilevia the propellent gas further forward in the barrel by devicesspecially arranged there (see, for example, U.S. Pat. No. 5,546,844).

The technical problems which form the basis of the present invention areon the one hand the handling and storage problems which exist or canarise in the different weapon systems due to the weight, themoisture-sensitivity, the risk of electric short-circuiting etc. of theshell, and on the other hand the specific risk for ETC cannons that thecartridge case burns on in the barrel owing to electric short-circuitingbetween the cartridge case and the barrel. This is because the modernconventional cartridge case is manufactured from electrically conductivemetal, usually brass. The burning-on is caused by the current and/or thevoltage used during firing being intentionally or unintentionallyconducted across to the cannon/artillery piece via the barrel. Moreover,the fact that the cannon/artillery piece becomes live constitutes anextra disadvantage for the gun crew.

It is therefore highly desirable to produce a new type of ammunitionwhich is different from the abovementioned electrically conductive metalammunition, has a considerably lower projectile weight than allcomparable ammunition for conventional weapon systems and moreover iselectrically insulated in order to prevent short-circuits and tominimize the risk of all or parts of the cartridge case burning on inthe chamber or in the barrel.

PRIOR ART

Patent specification U.S. Pat. No. 6,186,040 describes a known plasmatorch arrangement for electrothermal and electrothermochemical cannonsystems where the necessary current and voltage are transferred to theplasma fuse via the rear part of the latter and then on to earth via thecase jacket of the round and the barrel of the cannon system. A majorproblem in plasma cannons of this type is therefore that they use thecannon barrel as a counterelectrode, and so these constructions alsoapply current and voltage to the cannon barrel itself and thus otherimportant parts of the weapon system concerned. Apart from the obviousdisadvantages of this, such as the risk of personal injury as a resultof electrical hazard and short-circuiting of the weapon system, it isclear that there is a considerable risk of the cartridge case burning onin the barrel when current and voltage are conducted across to thecannon.

An electrothermal firing arrangement with associated ammunition is alsoknown from U.S. Pat. No. 5,331,879, where the arrangement comprises abarrel which comprises an inner “combustion chamber part”, in which thepropellent charge burns, and an outer “projectile guide part” foraccelerating the projectile. The ammunition comprises an only partlyelectrically insulated cartridge case, as the front part adjacent to theprojectile consists of a front electrode which is electrically connectedto the said projectile guide part of the barrel. The current transferpath for the arrangement via the ammunition therefore consists of anearthed metal breech block for current supply, a first and secondelectrode of the round between which a metal wire runs, and the barrelitself. It is easy to see that such a design of a cannon barrelconstitutes neither a conventional construction nor a valid solution forconventional use in the field in a real weapon system, as opposed tohere in a theoretical laboratory construction. For example, theammunition round does not have a cartridge case proper, as the cartridgecase and the firing device are the same component here. The projectilecan therefore be considered to be mounted directly at the end of a fuse,as a result of which the round is always armed and cannot be disarmedwithout being destroyed at the same time.

It is true that the combustion chamber part and the projectile guidepart have been insulated from one another via a high-voltage seal madeof rubber or silicone rubber arranged between them, but the rubber willage very rapidly and be destroyed by use, after which the problems ofshort-circuiting etc. described above will occur. Moreover, it has beennecessary to insulate, in addition to a small area intended for a cableterminal for the front electric connection, the entire front part of thebarrel with a surface coating on its outside.

In addition to the constructions with metal barrels exemplified above,alternative barrels made in their entirety of non-conductive materialhave also been manufactured. An example of these is inter alia thegrenade sleeve of the Carl-Gustaf anti-tank rifle, which is todaymanufactured from wound, glass-fibre-reinforced epoxy. In this case,however, the selection of material would be due to the resulting weightreduction.

One problem in the use of such non-metal barrels for conventionalbarrels as well is that the pressure from the combustion of thepropellent charge will burst the barrel when the latter is closed at therear end, which is of course the case in, for example, conventionalartillery pieces, anti-tank weapons, cannons for tanks etc.

OBJECTS AND FEATURES OF THE INVENTION

An important object of the present invention is therefore to produce anew type of insulated or insulating cartridge case and ammunition roundprimarily for electrothermochemical weapon systems, which cartridge caseand which ammunition round are insulated in such a way that theyconsiderably reduce or completely eliminate all the abovementionedproblems and in particular the problems of the application of currentand voltage to the barrel and other sensitive parts of the weapon systemand also the risk of the cartridge case burning on in the said barreland chamber.

Another object of the present invention is to produce cartridge casesand ammunition for use in weapon systems other than the saidelectrothermochemical weapon systems, which cartridge cases and whichammunition moreover have a considerably lower total weight compared withconventional ammunition.

It is also an object of the present invention to produce a new methodfor manufacturing cartridge cases and ammunition which are insulated inrelation to their surrounding environment, that is to say which are notonly electrically insulated but which can also be insulated with regardto water, moisture, temperature etc.

The said objects, and other aims not listed here, are achieved withinthe scope of what is stated in the present independent patent claims.Embodiments of the invention are indicated in the dependent patentclaims.

The solution according to tie present invention is, in a way describedin greater detail below, to replace the normally heavier, metalcartridge case with a lighter case which is electrically insulated orwhich is made of a material which does not conduct current, for examplea plastic, ceramic or glass-fibre material etc. The result of the saidinsulation or replacement is that electric flashover, that is to say ashort-circuit, normally cannot happen, and in most cases a considerableweight reduction as well and also thermal insulation etc. are obtainedwhen a metal case is replaced with a non-metal case.

Examples of suitable replacement materials are polyethylene,glass-fibre-reinforced epoxy etc.

According to the present invention, an improved cartridge case andammunition round comprising the said cartridge case have therefore beenproduced, which are characterized in that:

-   the casing of the cartridge case comprises or consists of one or    more insulated or insulating shells, layers or surfaces for, at    least electrically, insulating the casing of the cartridge case from    the barrel of the weapon system and also preferably from at least    the bottom and/or firing device of the ammunition round as well, but    preferably also from the rest of the ammunition round, when the    round is used, and also preferably from at least the bottom and/or    firing device of the ammunition round as well, but preferably also    from the rest of the ammunition round, when the round is stored and    handled.

According to other aspects of the cartridge case and the ammunitionround according to the invention:

-   the casing of the cartridge case comprises a load-bearing case    shell, for example in the form of a conventional cartridge case    manufactured from an electrically conductive metal, for example    brass, and also at least one inner and/or outer coating, surface or    layer, of which at least the shell or one inner and/or outer    coating, surface or layer is dielectric for electric insulation of    the case in relation to at least the barrel and preferably also to    the bottom and/or firing device of the ammunition round, but    preferably also to the rest of the ammunition round;-   the cartridge case has a casing which comprises at least one inner    and/or outer coating, surface or layer which is a mechanically    applied layer or a chemically or electrochemically applied surface;-   at least one inner and/or outer coating, surface or layer consists    of a material applied by phase transformation, such as vaporization    and condensation to form an insulating film, preferably a dimeric or    polymeric raw material comprising hydrocarbons, such as    poly-para-xylylene or another suitable plastic;-   at least one inner and/or outer shell or layer consists of    shape-imitating shrink film or flexible tube made of preferably    non-conductive material, such as rubber or plastic;-   the casing of the cartridge case comprises or consists of a    non-conductive or electrically insulating load-bearing material,    shell, layer or surfaces, such as hard plastic, ceramic, rigid    rubber, fibre composite etc.;-   the casing of the cartridge case comprises or consists of a    relatively flexible non-conductive or electrically insulating shell    or layer which is constructed from a glass-fibre laminate comprising    woven glass-fibre fabric and glass-fibre thread, for example    glass-fibro-reinforced epoxy in the form of a case jacket wound in a    number of plies;-   the casing of the cartridge case has a thread winding which is    arranged along the case jacket at a winding angle α defined for each    ply to the longitudinal axis Y of the case, and which casing    includes several different thread-winding angles α for bringing    about locking of the glass fibre, preferably at least 4 different    angles α in relation to the longitudinal axis Y of the case;-   the firing device is arranged detachably on a bottom integrated with    the casing of the cartridge case or on a separate bottom piece    arranged preferably demountably with the casing;-   the separate bottom piece is manufactured with an interference fit    to the cartridge case jacket which is greater than the expansion    possibility of the round in the cartridge chamber plus the maximum    compression which can be brought about by the inner overpressure    when firing takes place;-   the round also comprises at least one projectile, and, enclosed in    the cartridge case, a propellent charge which essentially follows    the inner dimensions of the case;-   the shrink film or the tube is arranged directly on the outside of    the propellent charge;-   the propellent charge consists of a cartridge-shaped charge which is    surrounded by an outer shrink film or flexible tube for forming a    cartridge-shaped, and if appropriate vacuum-packed, round which    stands up to normal handling of the round;-   the bottom piece is electrically non-conductive, suitably made of    glass-fibre epoxy, and arranged on the rear end of the casing in a    tight-fitting manner by means of screw-thread cutting, adhesive    bonding or by means of another connection suitable for the function;-   the bottom and/or the rear end of the firing device comprise(s) an    electric connection, by means of which the ammunition round, once    introduced into the chamber of the weapon concerned, is in electric    contact with the high-voltage source of the weapon concerned via the    firing device;-   the firing device comprises an outer, electrically conductive metal    combustion chamber which is arranged projecting from and detachably    fastened to the rear end of the cartridge case, and a central    electrode arranged inside the chamber, the central electrode    comprises a first, “input” electric connection, the rear end of the    combustion chamber comprises a second, “output” electric connection,    an electrically insulating device is arranged between the said two,    “input” and respectively “output”, electric connections and along    the entire length of the combustion chamber between the said “input”    electric connection and a front opening arranged on the plasma    torch, at least one but preferably more electric conductors extend    inside the combustion chamber and the electrically insulating    device, between the first, “input” electric connection and the front    opening of the combustion chamber, the combustion chamber, the    electric conductors and the central electrode all being electrically    conductive, as a result of which the current transfer path, the    polarity of which can be changed, for the necessary current and    voltage is therefore arranged so as to run from the first, “input”    electric connection and on to the front opening of the combustion    chamber via the electric conductors for ionization of these to form    a very hot, expansive plasma, which squirts out through the said    front opening, for igniting the propellent charge, and finally from    the plasma and the front opening of the combustion chamber back to    the “output” electric connection via the casing of the combustion    chamber;-   the firing device of the ammunition round can consist of a fuse for    use of the cartridge case and the ammunition round in other more    conventional weapon systems than the said electrothermal and/or    electrothermochemical weapon systems.

According to the invention, furthermore, the method for manufacturingthe said cartridge case and ammunition is characterized in that:

-   at least one of the shells or layers which form part of the casing    of the cartridge case is manufactured by glass-fibre thread being    wound with resin in thin layers with varying winding angles α    sandwiched with woven glass-fibre fabric so that a plurality of    winding plies/laminate layers are obtained after hardening.

According to other aspects of the method for manufacturing the cartridgecase and the ammunition round according to the invention:

-   for every such winding ply/laminate layer, a fibre winding with    fibre angles of essentially roughly 90° to the longitudinal axis of    the tube on the inside and +/− roughly 15-25°, preferably +/−20°, on    the outside is selected, and a number of such winding plies are laid    on top of one another and sandwiched with woven glass-fibre fabric    between a number of the thread-winding plies so that an essentially    flexible case jacket is obtained, as a result of which the casing of    a round introduced into the cartridge chamber tolerates being    expanded towards the walls of the cartridge chamber by the inner    overpressure inside the cartridge case brought about when firing    takes place without for that reason cracking, delaminating or    disintegrating;-   at least one of the shells or layers which form part of the casing    of the cartridge case is manufactured by an innermost, tightly woven    glass-fibre fabric first being applied to a winding and shaping tool    which is rotated while the fabric is draped over it, the last piece    of the woven glass-fibre fabric being laid so that a small overlap    is formed, after which a first winding ply of glass-fibre thread in    resin is wound with a fibre angle to the longitudinal axis of the    tube of essentially 90°, followed by two or more winding plies of    thread with a fibre angle, which is varied for the component plies,    of on the one hand roughly +15-25°, preferably +20°, and on the    other hand roughly −15-25°, preferably −20°, after which the    subsequent, thin winding plies/laminate layers are also given a    fibre winding with a fibre angle to the longitudinal axis of the    tube which varies between essentially roughly 90° and +/±roughly    15-25°, preferably +/±20°, as the thickness of the casing is built    up to roughly half-thickness, after which woven glass-fibre fabric    is sandwiched with fibre windings with a fibre angle of essentially    90° until full shell or layer thickness has been achieved;-   a relatively low winding speed is used, preferably roughly 4-6    m/min, while a relatively high thread tension, roughly    21-23N/roving, and a hardening cycle which comprises a plurality of    hardenings at increasing temperatures are selected;-   use is made of a hardening cycle of roughly 5 hours at roughly 80°,    followed by roughly 5 hours at roughly 120°, after which    after-hardening takes place for roughly 4 hours at roughly 140°;-   after shaping of a blank for the casing, this is cut and/or    turned/ground to essentially the desired length, thickness and    predetermined shape, after which a bottom piece is mounted on the    rear end of the casing in a tight-fitting manner, preferably by    adhesive bonding or screw-thread cutting;-   the bottom piece is manufactured from glass-fibre epoxy, either by    glass-fibre thread and/or woven glass-fibre fabric being given    during shaping the form of a hammock where only tensile loads in the    fibres can occur or by glass-fibre thread and/or woven glass-fibre    fabric being given during shaping the form of a plane bottom so that    pressure loads can also occur, after which the bottom piece, after    shaping and hardening have been completed, is then turned out,    attention being paid to obtaining the correct interference fit for    the casing concerned;-   the bottom piece is manufactured from an electrically conductive    material, suitably from metal;-   an insulation coating is applied over all the shell or layer    surfaces of the cartridge case concerned which are accessible to gas    by phase transformation via a number of phases, a dimeric or    polymeric raw material being vaporized so that the polymer or the    dimer is first transformed from solid phase to gas phase and then,    at a further increased temperature, is transformed to a reactive    monomer gas which is made to condense and polymerize, a thin    insulating plastic film layer being deposited on all the free    surfaces of the cartridge case;-   the condensation of the reactive monomer gas to form an insulating    film takes place under low pressure, preferably in a vacuum.

The use of such cartridge cases and ammunition according to theinvention is characterized in that the firing device of the ammunitionround can consist of a fuse for use of the cartridge case and theammunition round in other more conventional weapon systems than the saidelectrothermal and/or electrothermochemical weapon systems.

ADVANTAGES OF THE INVENTION

The advantages include the fact that, compared with the conventionalmetal cases, a considerable weight saving (roughly 70%) is obtainedwhile the ammunition quantity remains the same. Alternatively, if thestorage space allows, a greater quantity of ammunition can be carried inspite of an unchanged total weight.

From a technical point of view, manufacturing is simple, as a result ofwhich the cases can be manufactured with uniform and high quality for alow manufacturing cost. The form and execution selected for the windingplies result in tight laminate shells, which prevent overpressure beingbuilt into the casing of the case, a high expansion capacity without thecase cracking, and also the laminate sealing itself the more theoverpressure in the round increases. Moreover, the cases have greatimpact-resistance at the same time as they tolerate a certaindelamination in the event of careless handling.

By using a cartridge case made of electrically insulating material, thatis to say non-conductive plastic, glass fibre, ceramic etc., or by usinga metal case which has been provided with a coating, surface or layerwhich insulates the case electrically, for example by vaporization of aplastic to form an insulating plastic film of suitable thickness, therisk of flashover, that is to say electric short-circuiting, has on thewhole been eliminated.

Even if the current should happen to be conducted across to thecannon/artillery piece when firing of a round takes place, the cartridgecase will not burn on in the barrel, which is often the result when thecartridge case is made of metal.

LIST OF FIGURES

The invention will be described in greater detail below with referenceto the accompanying figures, in which

FIG. 1 is a diagrammatic perspective view of a round comprising aninsulated or insulating cartridge case according to the presentinvention, which round is here intended in particular for anelectrothermochemical weapon system;

FIG. 2 is a diagrammatic longitudinal section through parts of the roundaccording to FIG. 1, which longitudinal section shows inter alia aplasma torch arranged inside the insulated or insulating cartridge case;

FIG. 3 is a longitudinal section through parts of a diagrammatic weaponfor firing the round according to FIG. 1;

FIG. 4 is a diagrammatic longitudinal section through parts of thecartridge case for the round according to FIG. 1;

FIG. 5 shows diagrammatically a perspective view of an alternativecartridge case made of, for example, glass-fibre-reinforced epoxy foruse in a round according to the invention, and

FIG. 6 is a diagrammatic longitudinal section through the cartridge caseaccording to FIG. 5.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to FIG. 1, a perspective view is shown of an ammunitionround 1 comprising an, at least electrically, insulated or insulatingcartridge case 2 according to the present invention. Here, the round 1is intended in particular for an electrothermochemical (ETC) weaponsystem comprising armour-piercing dart ammunition for use in tanks,combat vehicles and various anti-tank weapons but also in, for example,combat aircraft, anti-aircraft weapons and other artillery.

It will be understood, however, that the round 1 shown is not onlyintended for such ETC ammunition and that it can also include severaldifferent sizes and projectile types depending on the area of use andcalibre. Here, however, it is at least the commonest ammunition typestoday, between roughly 25 mm and 160 mm, which are concerned.

The expressions “at least electrically insulating” or “at leastelectrically insulated” mean that the material, the case etc. sodesignated can also function as insulating or be insulated in relationto the surrounding environment with regard to water, moisture,temperature etc.

FIG. 2 shows a diagrammatic longitudinal section through parts of afirst embodiment of the round 1 according to FIG. 1, which round 1 alsocomprises, in addition to the said insulated or insulating cartridgecase 2, a projectile 4 mounted at the front end 3 of the cartridge case2, a firing device in the form of a plasma torch 5 arranged at the rear,flanged end 6 of the round 1, and a propellent charge 7 which isenclosed in the cartridge case 2 and is indicated diagrammatically onlyin the centre of the case 2. Preferably, however, the entire cavity 8 ofthe case 2 is filled with a propellent charge 7 which can consist of asolid powder or a suitable liquid propellant. The solid propellentcharge 7 suitably consists of what is known as a progressive perforatedpowder provided with a large number of holes in the form of one or more,for example cylindrical, bars, plates, blocks etc., which powderessentially follows the inner dimensions of the case 2, or of a chargecomprising grain powder, also known as powder pellets 9, for example acompacted NC powder grain charge. In this connection, the said powdergrains 9 have first been treated with a suitable chemical in order tobring about adhesion between the individual grains 9, after which thegrains 9 are pressed together to form a charge 7 with a desired shapedetermined by the cavity 8. Alternative embodiments of the powder charge7 also include multi-perforated double-base (DB) powder with inhibition,Fox 7, AND, nitramine, GAP and other known powder types.

It applies generally that the cartridge case 2 comprises an, at leastelectrically, insulating and/or electrically insulated casing 10. Thiscasing 10 can then consist of only one or the same essentiallyhomogeneous material layer, shell or laminate 11 which is thendielectric (that is to say non-conductive), for example a fibrecomposite, or of a combination of several different shells, layers orsurfaces 11, 12, 13, where at least one of these acts in an electricallyinsulating manner for the others and for the cartridge case 2 as awhole.

A combined casing 10 (compare FIG. 4) can, for example, consist of anessentially supporting or load-bearing shell 11 and also at least oneinner 12 and/or outer 13 mechanically applied layer or chemicallyapplied surface, that is to say coating. The essentially supporting orload-bearing shell 11 is preferably non-conductive and then suitablymade of glass-fibre epoxy, rubber etc., but the said shell 11 can beconductive, in which case at least one of the inner and/or outer layersor surfaces 12, 13 of the casing 10 is then dielectric in order to bringabout the said electric insulation of the inside and/or outside of thecasing 10 in relation to at least the barrel 14 and preferably also tothe plasma torch 5.

Preferably, the casing 10 (see FIGS. 5 and 6) is constructed from aglass-fibre laminate comprising a thin tight woven E-glass fibre fabricon the inside, suitably what is known as a Fothergill fabric, on theoutside of which E-glass fibre thread (for example R25 glass) is woundwith resin in thin layers with varying winding angles α sandwiched withfurther woven E-glass fibre fabric (see below).

In an example of the said embodiment of a cartridge case 2 with aconductive shell 11, the case comprises a load-bearing, metal shell 11,on which a plastic film coating 12, 13 (see below) has been applied. Seein particular FIG. 4 which shows a load-bearing shell 11 made of brasswhich has been insulated with, for example, shrink film or a plasticfilm coating 12, 13 in order to bring about electric insulation inrelation to the barrel 14. Here, load-bearing 11 or supporting shellmeans that a load-bearing shell 11 in itself stands up to normalstresses without being deformed appreciably during handling of the case2 and the round 1, while supporting means an essentially flexible shellwhich is, for example, arranged directly on the outside of thepropellent charge 7 without an inner, rigid case casing being present,the shell together with the propellent charge 7 then standing up to thesaid normal handling of the round 1. An example (not shown) of a roundcomprising a supporting shell will consist of an inner cartridge-shapedcharge which is enclosed in an outer shrink-film or flexible tube whichsurrounds the charge and is shaped according to the saidcartridge-shaped charge. If appropriate, extra rigidity can be obtainedby vacuum-packing.

In this connection, the supporting shell is arranged so that it extendsbetween the projectile and the bottom piece with a rigidity as isrequired for the function. In this embodiment, after firing the finishedround, only the metal bottom of the cartridge case remains, and the restis combusted in the barrel.

In the embodiments of the cartridge case 2 according to the inventionshown in particular in FIGS. 4 and 6, these comprise an at leastelectrically insulating and/or electrically insulated casing 10 whichconsists of a load-bearing shell 11, on the outside of which an outerlayer or surface 13 is (see FIG. 4) or can be arranged (FIG. 6). Eitherof or both the shell 11 and the outer layer or surface 13 is thendielectric, the layer suitably consisting of the abovementionedshape-imitating shrink film or elastic tube, while the surface consistsof a suitable insulating coating. If the shell 11 consists of aglass-fibre composite, for example, the said layers or surfaces 12, 13can instead consist of, for example, a coating which increases wearprotection or moisture protection in order to bring about a reduction ofthe stresses on the shell 11 or respectively an improvement of themoisture protection for the round 1. An example of a suitable electricinsulation coating is a dimeric or polymeric raw material comprisinghydrocarbons, such as poly-para-xylylene.

In the other embodiment of the cartridge case 2 according to theinvention shown in FIG. 6, the case has an electrically insulatingcasing 10 which comprises a relatively flexible laminate shell 11 in theform of a case jacket 15, wound in several plies, suitably made ofglass-fibre-reinforced epoxy, for example of polyethylene like theabovementioned barrel for the Carl-Gustaf anti-tank rifle. Theglass-fibre reinforcement comprises a number of wound plies of threadand/or fabric, preferably both. In a special embodiment of the cartridgecase 2, the casing 10 is constructed from a glass-fibre laminatecomprising a thin tight woven E-glass-fibre fabric on the inside,suitably what is known as a Fothergill fabric, on the outside of whichE-glass fibre is wound with thin layers sandwiched with further wovenE-glass-fibre fabric. Suitably, the thread-winding is arranged along thecase jacket 15 at a winding angle α defined for each ply, which variesin relation to the longitudinal axis Y of the case 2. In order to bringabout locking of the glass fibre, it is essential that the casing 10contains a number of different fibre directions which lock one another,preferably at least 4 different directions in relation to thelongitudinal axis Y of the case 2, for example essentially roughly 0°,90° and +/− roughly 15-25°, preferably +/−20°.

In the embodiment according to FIGS. 5 and 6, a separate bottom piece 16(not shown), which can be either electrically conductive ornon-conductive, suitably made of metal material or of glass-fibre epoxy,is also arranged on the rear end 6 of the case jacket 15 in atight-fitting manner by means of screw-thread cutting, adhesive bondingor by means of another connection suitable for the function (compareFIG. 1 where the round 1 instead comprises a bottom 16 which isintegrated with the rest of the casing 10 of the cartridge case 2). Inthe embodiment according to FIGS. 5 and 6, the bottom piece 16,including the plasma torch 5, can therefore be arranged unscrewably fromthe rest of the cartridge case 2 or be more or less permanently fastenedthereto. The detachably arranged plasma torch 5 also affords thepossibility of replacing the plasma torch 5 with a conventional fuse, asa result of which the round can thus be used in a conventional weaponsystem, that is to say in the abovementioned only gas-operated systemsas well.

However, when the round 1 according to the embodiment with the separatebottom piece 16 is fired, there is an obvious risk that undesirablepressure forces can penetrate between the cartridge case jacket 15 andthe bottom piece 16. These pressure forces can then split apart thelaminate in the case jacket 15 and in the bottom piece 16. In order tominimize the risk of this happening, the separate bottom 16 ismanufactured with an interference fit to the cartridge case jacket 15which is greater than the expansion possibility of the round 1 in thecartridge chamber plus the maximum compression which can be broughtabout by the inner overpressure when firing takes place. Moreover, arubber ring seal (not shown) can be mounted between the cartridge casejacket 15 and the bottom piece 16 to bring about extra sealing.

The abovementioned metal bottom 16 and/or the rear end 30 of the plasmatorch 5 (see below) lie(s) against the chamber 17 of the weaponconcerned (see FIG. 3), as a result of which the plasma torch 5 is inelectric contact with a high-voltage source 18, the polarity of whichcan be changed, via an electric connection 19. After the current/voltagehas been transferred to the fuse/plasma torch 5, it is returned via theouter casing 15 of the latter 5 to its rear part 30 and the electricconnection 19. By virtue of the fact that the current follows theeasiest path through the plasma torch 5, which path is via the plasmaformed, and because the cartridge case 2 according to the embodimentsdescribed above consists of one or more materials which do not conductcurrent or voltage across to the barrel 14, there is therefore no riskof flashover/short-circuiting or of the cartridge case 2 burning on inthe weapon/cannon concerned.

In the embodiments of the round 1 shown in the figures (see inparticular FIG. 2), the projectile 4 comprises an armour-piercing dart20 with a guide cone or guide fins 21, which armour dart 20 is at leastpartly enclosed in and supported inside the case casing 10 by amulti-part dart support body 22. Arranged around the body 22 is a belt23 made of plastic for sealing the round 1 in relations to the inside ofthe barrel 14. A connection 24 in the form of, for example, grooving,adhesive bonding etc. connects the projectile 4 to the casing 10 of thecartridge case 2 (see FIG. 2). Amour-piercing dart ammunition 1 achievesits great effect because the dart 20 has a considerable weight (densityroughly 17-20 g/cm³, for example tungsten).

The plasma torch 5 (see FIG. 2), which constitutes the equivalent of theETC round 1 to a conventional fuse with suitably the same or similarexternal shape as the latter, comprises an outer, electricallyconductive combustion chamber 25 and, arranged inside the latter, acentral electrode 26. Here, the combustion chamber 25 is in the form ofa metal cylindrical tube which projects from and is detachably fastenedto the rear end 6 of the cartridge case 2 by means of a suitableexternal screw thread 27. In the embodiment shown in FIG. 2, the plasmatorch 5 is screwed firmly to the bottom 16 integrated with the casing 10of the cartridge case 2 or to the bottom piece 16 arranged demountablywith the casing 10.

The plasma torch 5 also comprises a front opening 28. The centralelectrode 26 comprises a metal, cylindrical contact device 29 forbringing about a first “input” electric connection 19 a. The rear end 30of the combustion chamber 25 has a metal flange 31 as the “output”electric connection 19 b. An electrically insulating tube 32 (seeFIG. 1) is arranged between the said two, “input” and respectively“output”, electric connections. Extending inside the combustion chamber25 and along its entire length between the said front opening 28 and themetal contact device 29 is at least one but preferably more electricconductors (not shown), such as thin metal wires, wool, rolled metalfoil, net structures, porous thin films etc. made of, for example,aluminium, copper or steel etc. The combustion chamber 25, the contactdevice 29, the electric conductors and the central electrode 26 are allelectrically conductive, and so the current path, the polarity of whichcan be changed, runs from the metal contact device 29, on to the frontopening 28 of the combustion chamber 25 via the electric conductors,which are then ionized to form a very hot and expansive plasma whichsquirts out and ignites the propellent charge 7 through the said frontopening 28. From the plasma and the front opening 28 of the combustionchamber 25, the current is conducted back to the “output” electricconnection 19 b via the casing of the combustion chamber 25. For a moredetailed description of the design of the plasma torch, reference ismade to our Swedish application entitled “Plasma torch forelectrothermochemical weapon system, ETC round for use in such a weaponsystem and method for firing the said round”.

METHOD AND DESCRIPTION OF FUNCTION

The method for manufacturing the cartridge case 2 and the ammunition 1according to the embodiment comprising a casing 10 and a separate bottompiece 16 made of glass-fibre epoxy is as follows.

A first design philosophy was based on manufacturing a cartridge case 2which was as strong as possible, that is to say that the shell 11 of thecase jacket 15 would be rigid. For each winding ply/laminate layer 11,12, 13, a fibre winding with fibre angles of essentially roughly 90° tothe longitudinal axis of the tube on the inside (like on a conventionalspool) and +/− roughly 20° on the outside was selected. In order toobtain an extra strong case jacket 15, many such winding plies 11, 12,13 were laid one on top of another. It was found that such casings 10burst during test firing due to the great risk of crack formation andthe build-up of overpressure in the glass-fibre laminate. As mentionedabove, it is an absolute requirement that the cartridge case 2 can beremoved from the cartridge chamber after the shell has been fired. Thisrequirement is complicated or rendered impossible if the casing 10 isnot in one piece.

The current design philosophy, which forms the basis for the case 2 andthe ammunition 1 according to the present embodiment of the invention,is that the casing 10 is instead essentially flexible, that is to saythat the casing 10 of a round 1 introduced into the cartridge chambertolerates being expanded towards the walls of the cartridge chamber bythe inner overpressure inside the cartridge case 2 brought about whenfiring takes place without for that reason cracking, delaminating ordisintegrating. This is achieved by sandwiching woven glass-fibre fabricbetween several of the thread-winding plies. In this connection, thesaid inner overpressure which is handled can be assumed to vary fromroughly 450 MPa to at least 750 MPa depending on the calibre, type etc.of the round.

Manufacture is started by an innermost, tightly woven glass-fibre fabricfirst being applied to the winding and shaping tool, while it is ensuredthat any air bubbles are carefully pressed out of the laminate so thatthere is no risk of air pockets being built into the laminate. Thesimplest way of doing this is to rotate the tool while the fabric isdraped over it. The last piece of the glass-fibre fabric is laid so thata small overlap is formed. Then, a first winding ply of glass-fibrethread in resin is laid with a fibre angle to the longitudinal axis ofthe tube of essentially 90°, followed by two winding plies of threadwith a fibre angle of on the one hand roughly +20° and on the other hand−20°. The subsequent, thin winding plies/laminate layers 11, 12, 13 arethen given a fibre winding with a fibre angle to the longitudinal axisof the tube which varies between essentially roughly 90° and +/− roughly20° as the thickness of the casing 10 is built up to roughlyhalf-thickness. After that, woven glass-fibre fabric and fibre windingswith a fibre angle of essentially 90° are sandwiched until full casethickness has been achieved. Suitably, two cartridge cases 2 are woundsimultaneously by virtue of the blank of the case 2 being manufacturedin such a way that, after winding has been completed, the blank can bedivided into two equal parts, the cut taking place between the rear andtherefore rougher ends 6 of the two cases.

The winding speed, thread tension and hardening cycle are selectedcarefully so as to obtain optimum and economical manufacture. Thewinding speed should be relatively low, 4-6 m/min and preferably roughly5 m/min, while the thread tension should be quite high, roughly 21-23N/roving and preferably 22 N/roving, in order to avoid any risk ofdelamination. In order further to minimize the risk of delamination, useis suitably made of a hardening cycle comprising a plurality ofhardenings at increasing temperatures, for example a hardening cycle ofroughly 5 hours at roughly 80°, followed by roughly 5 hours at roughly120°, after which after-hardening takes place for roughly 4 hours atroughly 140°.

After shaping of the blank for the case jacket 15, this is cut andturned/ground to the desired length, thickness and predetermined shape,for example comprising the flange 6, after which a bottom piece 16 ismounted on the rear end 6 of the case jacket 15 in a tight-fittingmanner, preferably by adhesive bonding by means of epoxy adhesive, butuse can also be made of screw-thread cutting or another connection (notshown) suitable for the function. Any steel components, such as theplasma torch 5 and the steel bottom 16 if one is used, aresurface-treated before adhesive bonding.

When a bottom 16 made of glass-fibre epoxy is used, this can bemanufactured according to two methods, either via a hammock method whereonly tensile loads in the fibres can occur or via a plane bottom methodso that pressure loads can also occur. After shaping and hardening havebeen completed, the bottom piece is then turned out, attention beingpaid to obtaining the correct interference fit as above.

Mounting of the fuse or alternatively the plasma torch is effected viascrew-thread cutting so that they can be interchanged. Mounting of theprojectile, propellent charge and other components included in thefinished round is carried out in a conventional way.

The method for manufacturing the cartridge case 2 and the ammunition 1according to the embodiment comprising a metal casing 10 with electricinsulation coating 12, 13 is as follows. An example of such a coating12, 13 is what is referred to as polymer vaporization.

This coating 12, 13 is applied over a conventional cartridge case 2 viathree phases comprising vaporization of a dimeric or polymeric rawmaterial comprising hydrocarbons (plastic), such as poly-para-xylylene,the polymer or the dimer first, at roughly 150° C., being transformedfrom solid phase to gas phase and then, at a further increasedtemperature of roughly 650° C., being transformed to a reactive monomergas which is finally made to condense (that is to say polymerize) on thecartridge case 2 which is at room temperature and under vacuum, a thininner and outer insulating plastic film layer 12, 13 being deposited onall the free surfaces of the case 2 with a thickness of roughly 20-70μ.

The resulting highly pure, hole-free, tough and elastic polymer film 12,13 is completely smooth and has a low friction coefficient (as a resultof which the cartridge case is provided with spontaneous lubrication),high abrasion-resistance, low water absorption, and also a highdielectric constant of roughly 200 V/μm. Moreover, the polymer film isnon-sensitive to gases, solvents, chemicals, water and moisture.

ALTERNATIVE EMBODIMENTS

The invention is not limited to the embodiment shown but can be variedin different ways within the scope of the patent claims. It is clear,for example, that an insulating coating and protective layer can also beobtained by means of conventional varnishing of the round and the case.Compared with the polymer vaporization described above, however,varnishing has the disadvantages of higher permeability and worseadhesion, and the varnish can also crack.

Materials other than polyethylene, glass-fibre-reinforced epoxy etc. anddifferent thread tension, fibre angles, hardening cycles etc. andwinding plies may be possible in future. It is clear that the number,size, material and shape of the elements and components included in theround 1 and the cartridge case 2, for example the bottom piece 16, thefabric, resin and thread type etc., are adapted according to the weaponsystem(s), calibres, active part etc. and also the surroundingenvironment concerned. It is therefore clear that the invention is in noway limited to the embodiments shown in particular, but that every otherconfiguration according to the above falls within the inventive idea.

1. A cartridge case (2) and ammunition round (1) primarily for at leastone of electrothermal or electrothermochemical weapon systems wherein:the ammunition round (1) comprises the cartridge case (2) having acasing (10), a bottom or a bottom piece (16), and a firing device (5),which firing device (5) comprises an electric connection (19) by meansof which the ammunition round (1) is in electric contact with theweapon, wherein the casing (10) including the bottom or the bottom piece(16) comprises one or more insulated or insulating shells, layers orsurfaces (11, 12, 13) for, at least electrically, insulating both thecasing (10) of the cartridge case (2) and its bottom or bottom piece(16) from the rest of the ammunition round (1) including its firingdevice (5) when the round (1) is stored and handled and, when the round(1) is used, from a barrel (14) of the weapon system, wherein the casing(10) of the cartridge case (2) comprises a load-bearing case shell (11)in the form of a cartridge case (2) manufactured from an electricallyconductive metal of which at least one inner or outer coating, surfaceor layer (12,13) is of dielectric material for the electric insulationof the cartridge case (2) in relation to the barrel (14) and also to therest of the ammunition round (1) including the firing device (5) and theammunition round (1).
 2. The cartridge case (2) and ammunition round (1)according to claim 1, wherein the cartridge case (2) has the casing (10)which comprises at least one inner or outer coating, surface or layer(12, 13) which is a mechanically applied layer, a chemically appliedlayer or electrochemically applied surface.
 3. The cartridge case (2)and ammunition round (1) according to claim 1, wherein the at least oneinner or outer coating, surface or layer (12, 13) comprises a materialapplied by phase transformation, including vaporization or condensationto form an insulating film (12, 13), a dimeric or polymeric raw materialcomprising hydrocarbons, including poly-parasylylene.
 4. The cartridgecase (2) and ammunition round (1) according to claim 1, wherein the atleast one inner or outer shell or layer (11, 12, 13) comprisesshape-imitating shrink film or flexible tube (11, 12, 13) made ofnon-conductive material, including rubber or plastic.
 5. An ammunitionround (1) with cartridge case (2) according to claim 4, wherein theround (1) comprises a propellent charge (7) and that the shrink film orthe tube (11, 12, 13) is arranged on the outside of the said propellentcharge (7).
 6. The ammunition round (1) with cartridge case (2)according to claim 5, wherein the propellent charge (7) comprises acartridge-shaped charge which is surrounded by the shrink film or theflexible tube (11, 12, 13) for forming at least one of acartridge-shaped or vacuum-packed round (1) which stands up to normalhandling of the round (1).
 7. The cartridge case (2) and ammunitionround (1) according to claim 1, wherein the casing (10) of the cartridgecase (2) comprises a non-conductive or electrically insulatingload-bearing material, shell, layer or surfaces (11, 12, 13), includinghard plastic, ceramic, rigid rubber, or fiber composite.
 8. Thecartridge case (2) and ammunition round (1) according to claim 1,wherein the casing (10) of the cartridge case (2) comprises a relativelyflexible non-conductive or electrically insulating shell or layer (11,12, 13) which is constructed from a glass-fiber laminate.
 9. Thecartridge case (2) and ammunition round (1) according to claim 8,wherein the casing (10) of the cartridge case (2) has a glass-fiberthread winding which is arranged along the case jacket (15) at a windingangle α defined for each ply to the longitudinal axis Y of the case (2).10. The cartridge case (2) and ammunition round (1) according to claim1, wherein the firing device (5) is arranged detachably on a bottom (16)integrated with the casing (10) of the cartridge case (2).
 11. Thecartridge case (2) and ammunition round (1) according to claim 1,wherein the firing device (5) is arranged detachably on a separatebottom piece (16) arranged demountably with the casing (10) of thecartridge case (2).
 12. The cartridge case (2) and ammunition round (1)according to claim 1, wherein the bottom piece (16) is made ofglass-fiber epoxy, and arranged to fit tightly on the casing (10) by aconnection means including screw-thread cutting or adhesive bonding. 13.The ammunition round (1) with cartridge case (2) according to claim 1,wherein the firing device (5) comprises a plasma torch (5).
 14. Theammunition round (1) with cartridge case (2) according to claim 1,wherein the firing device (5) of the ammunition round (1) comprises afuse for use of the cartridge case (2) and the ammunition round (1). 15.Method for manufacturing a cartridge case (2) and an ammunition round(1) primarily for electrothermal and/or electrothermochemical weaponsystems, which round (1) comprises a cartridge case (2) according toclaim 1, characterized in that at least one of the shells or layers (11,12, 13) which form part of the casing (10) of the cartridge case (2) ismanufactured by glass-fiber thread being wound with resin in layers withvarying winding angles α sandwiched with woven glass-fiber fabric sothat a plurality of winding plies/laminate layers (11, 12, 13) areobtained after hardening.
 16. Method for manufacturing a cartridge case(2) and an ammunition round (1) according to claim 15, characterized inthat for every such winding ply/laminate later (11, 12, 13), a fiberwinding with fiber angles of essentially roughly 90° to the longitudinalaxis of the tube on the inside and +/− roughly 15-25°, preferably +/−20°, on the outside is selected, and in that a number of such windingplies (11, 12, 13) are laid on top of one another and sandwiched withwoven glass-fiber fabric between a number of the thread-winding plies sothat an essentially flexible case jacket (15) is obtained, as a resultof which the casing (10) of a round (1) introduced into the cartridgechamber tolerates being expanded towards the walls of the cartridgechamber by the inner overpressure inside the cartridge case (2) broughtabout when firing takes place without for that reason cracking,delaminating or disintegrating.
 17. Method for manufacturing a cartridgecase (2) and an ammunition round (1) according to claim 1, characterizedin that at least one of the shells or layers (11, 12, 13) which formpart of the casing (10) of the cartridge case (2) is manufactured by aglass-fiber being applied to a winding and shaping tool which is rotatedwhile the fabric is draped over it, the last piece of the wovenglass-fiber fabric being laid so that a small overlay is formed, afterwhich a first winding ply of glass-fiber thread in resin is wound with afiber angle to the longitudinal axis of the tube of essentially 90°,followed by two or more winding plies of thread with a fiber angle,which is varied for the component plies, of on the one hand roughly+15-25°, preferably +20, after which the subsequent, windingplies/laminate layers (11, 12, 13) are also given a fiber winding with afiber angle to the longitudinal axis of the tube which varies betweenessentially roughly 90° and +/− roughly 15-25°, preferably +/−20°, asthe thickness of the casing (10) is built up to roughly half-thickness,after which woven glass-fiber fabric is sandwiched with fiber windingswith a fiber angle of essentially 90° until full shell or layer (11, 12,13) thickness has been achieved.
 18. Method for manufacturing acartridge case (2) and an ammunition round (1) according to claim 1,characterized in that a relatively low winding speed is used, preferablyroughly 4-6 m/min, while a relatively high thread tension, roughly 21-23N/roving, and a hardening cycle which comprises a plurality ofhardenings at increasing temperatures are selected.
 19. Method formanufacturing a cartridge case (2) and an ammunition round (1) accordingto claim 18, characterized in that use is made of a hardening cycle ofroughly 5 hours at roughly 80°, followed by roughly 5 hours at roughly120°, after which after-hardening takes place for roughly 4 hours atroughly 140°.
 20. Method for manufacturing a cartridge case (2) and anammunition round (1) according to claim 1, characterized in that aftershaping of a blank for the casing (10), this is cut and/or turned/groundto essentially the desired length, thickness and predetermined shape,after which a bottom piece (16) is mounted on the rear end (6) of thecasing (10) in a tight-fitting manner, preferably by adhesive bonding orscrew-thread cutting.
 21. Method for manufacturing a cartridge case (2)and an ammunition round (1) according to claim 1, characterized in thatthe bottom piece (16) is manufactured from glass-fiber epoxy, either byglass-fiber thread and/or woven glass-fiber fabric being given duringshaping the form of a hammock where only tensile loads in the fibers canoccur or by glass-fiber thread and/or woven glass-fiber fabric beinggiven during shaping the form of a plane bottom so that pressure loadsalso can occur, after which the bottom piece (16), after shaping andhardening have been completed, is then turned out.
 22. Method formanufacturing a cartridge case (2) and an ammunition round (1) comprisesa cartridge case (2) according to claim 1, characterized in that aninsulation coating (12, 13) is applied over all the shell or layersurfaces of the cartridge case (2) concerned which are accessible to gasby phase transformation via a number of phases, a dimeric or polymericraw material being vaporized so that the polymer or the dimmer is firsttransformed from solid phase to gas phase and then, at a furtherincreased temperature, is transformed to a reactive monomer gas which ismade to condense and polymerize, a thin insulating plastic film layer(12, 13) being deposited on all the free surfaces of the cartridge case(2).
 23. Method for manufacturing a cartridge case (2) and an ammunitionround (1) according to claim 22, characterized in that the condensationof the reactive monomer gas to form an insulating film (12, 13) takesplace under low pressure, preferably in a vacuum.
 24. Method formanufacturing a cartridge case (2) and an ammunition round (1) primarilyfor electrothermal and/or electrothermochemical weapon systems, whichround (1) comprises a cartridge case (2) according to claim 1,characterized in that an insulation coating (12, 13) is applied over allthe shell or layer surfaces of the cartridge case (2) concerned whichare accessible to gas by phase transformation via a number of phases, adimeric or polymeric raw material being vaporized so that the polymer orthe dimmer is first transformed from solid phase to gas phase and the,at a further increased temperature, is transformed to a reactive monomergas which is made to condense and polymerize, a thin insulating plasticfilm layer (12, 13) being deposited on all the free surfaces of thecartridge case (2).
 25. Method for manufacturing a cartridge case (2)and an ammunition round (1) according to claim 24, characterized in thatthe condensation of the reactive monomer gas to form an insulating film(12, 13) takes place under low pressure, preferably in a vacuum.